FR3099400A1 - Body part element comprising a heating film - Google Patents

Abstract

The invention relates to a method of manufacturing an element (1) for a bodywork part comprising successively the following steps: - Step A: a support element (10) having a first face (11) on which is fixed a support sheet (3) comprising at least one connection member (4). - Step B: a heating track is placed on the support element (10), substantially all of the heating track being disposed on the first face (11) of the support element (10), - Step C: on connects the heating track to the connection member (4), - Step D: the support element (10) is placed in a molding chamber of a mold defining the shape of the element for bodywork part, the first face (11) of the support member (10) facing the interior of the molding chamber and a plastic material is injected into the molding chamber in order to cover the heating track. Figure for the abstract: Fig. 1

Description

Element for a bodywork part comprising a heating film

The invention relates to the field of motor vehicles. And more particularly the field of the manufacture of a plastic element, intended to be mounted on a body part.

Many modern vehicles are fitted with plastic body parts which can be fitted, for example, to a rear hatch, a door panel, front and rear bumpers, a roof, etc.

In particular, since the introduction of driving assistance systems, it is necessary to place on certain plastic body parts sensors of different kinds, in order to measure external physical parameters representative of the external environment of the motor vehicle. . All the values of these parameters form information available in real time on the environment of the vehicle.

Bodywork elements are then used, attached to the bodywork part, having, for example, a radome function, that is to say an element transparent to electromagnetic waves protecting and hiding sensors.

For example, bumpers are now frequently equipped with proximity radars which help the driver during parking maneuvers of the motor vehicle at low speed.

Some sensors, such as the one cited in the example above, can see their normal operation disturbed by the presence of a layer of ice, snow or frost in the event of a temperature below 10 degrees Celsius. This layer of frost disrupts the normal passage of electromagnetic waves, which is a source of error for the evaluation of external physical parameters.

In order to avoid the deposit of ice, which not only renders the assistance system unusable, but which in addition can generate false alarms, it is essential to provide a de-icing system on the element for the bodywork part, for example on the area of the body part that serves as a radome.

Such a defrosting system is traditionally formed of a heating track, consisting of conductive wires capable of transforming electrical energy into thermal energy, is associated with two connection plates arranged at each end of the heating track in order to supply it with a current electric. This system is positioned on an element for a bodywork part located near a sensor. The thermal energy thus released makes it possible to locally defrost the room in the event that a layer of frost has formed.

It is known, for example, from document US2018/0269569, a heating radome comprising a flexible printed circuit (or PCB) forming a film which is stamped and molded in the back with a thermoplastic material. The printed circuit comprises a metal structure which is made by means of linear strips. The radome further comprises a connector for connecting the printed circuit to a power supply. The radome as described in this document requires a film large enough to be able to cover the entire area to be heated, which is equivalent to the surface of the radome. Thus, the two layers of plastic are separated from each other by the film which presents a significant bulk which makes the radome not very robust and not very tight. In addition, as the heating elements are supported by the film, the latter is present over the entire area to be heated. The transparent areas of the radome are reduced due to the presence of the film. Thus, the aesthetic quality of the radome is degraded.

The object of the invention is in particular to provide an element intended to be mounted on a bodywork part, for example a radome, which is more robust and aesthetic.

To this end, the subject of the invention is a method of manufacturing an element for a bodywork part comprising successively the following steps:
- Step A: a support element is produced having a first face on which is fixed a support sheet comprising at least one connection member.
- Step B: a heating track is placed on the support element, substantially all of the heating track being placed on the first face of the support element,
- Step C: the heating track is connected to the connection device,
- Step D: the support element is placed in a molding chamber of a mold defining the shape of the element for the bodywork part, the first face of the support element facing inside the chamber molding and a plastic material is injected into the molding chamber in order to cover the heating track.

The method as proposed by the present invention makes it possible to arrange one or more heating tracks at the places which require a heat input, which increases the defrosting efficiency. In addition, substantially all of the support element is separated from the molded layer only by the heating tracks, which allows reduced space between the layers and increased robustness of the final part. The aesthetic quality of the element for body parts is also improved thanks to the absence of a support sheet on almost all of this element. Indeed, the support sheet comprising the connection member can be easily moved to an area that is not very visible from outside the vehicle.

According to the invention, the support sheet is a flexible sheet, for example a flexible printed circuit, which can be subjected to mechanical torsion and makes it possible to save space compared to the use of rigid circuits or manual wired wiring. . The connection member may be formed of an electrically conductive plate or of a metal pin and the heating track may be formed of an electrically conductive wire.

According to other optional characteristics of the manufacturing process taken alone or in combination:
- the support element is a plastic film and step A comprises the following steps:
- a plastic film is produced,
- Is fixed on a first face of the film a support sheet comprising at least one connection member.

The fixing of the support sheet on the film makes it possible to guarantee the holding of the support sheet during the overmolding step of the film. This fixing can be done by gluing, welding or even the use of adhesive tape. The film 10 is produced by extrusion or lamination, but it is also possible to use an existing film on the market.
- the manufacturing process comprises the following step: a coating is deposited on a second face of the film, opposite the first face. The coating makes it possible to improve the resistance of the film to UV or to scratching. The coating can be a varnish or a coating resulting from a hardcoat treatment.
- the support element is a molded part and step A includes the following steps:
- a support sheet comprising at least one connection member is placed in a molding chamber of a mold defining the shape of the support element, a first face of the support sheet facing inside the molding chamber , and a plastic material is injected into the molding chamber in order to obtain a molded part covering the first face of the support sheet,
- Is placed on a second face of the support sheet, opposite to the first face, at least one connection member.
- the manufacturing process comprises the following step before step D: a means for protecting the connection member is placed on the support sheet so as to at least partially protect the connection member from the plastic material during the step D. The protection means has a space at least partially containing the connection member so that the latter is isolated from the plastic material injected during molding while retaining access to it for connection to a power supply electric.
- The heating track is connected to the connection member by welding. The type of welding can be of different nature, for example TC bonding or electric welding.
- the support sheet comprises a plurality of connection members electrically connected to each other by connection means integrated into the support sheet and steps B and C consist in arranging a corresponding number of heating tracks on the support element and in connecting each heating track to a connection member. It is then possible to arrange heating tracks independently, which facilitates the distribution of the heating zones according to need and improves the aesthetic appearance of the radome.
- The heating track is fixed on the support element by gluing or by local melting of the support element. This attachment can also be made by soldering with tin.
- the heating track comprises a material chosen from copper, tungsten, or an alloy of copper and tungsten.
- the support sheet is made from a sheet of silicone, polyolefin (polyethylene or polypropylene), thermoplastic elastomer (TPE), polyester, or polyamide. The backing sheet can also be epoxy. The material which is overmolded on the support sheet is chosen so that it is chemically compatible with the film to ensure good bonding and guarantee a minimum interface defect.

The invention also relates to an element for a bodywork part comprising a first transparent plastic layer, a second transparent plastic layer, a heating track arranged between the transparent plastic layers and connected to a connection member, substantially all of the heating track being in direct contact with the first and second layers.

Brief description of figures

The invention will be better understood on reading the following description given solely by way of example and made with reference to the appended drawings in which:

FIG. 1 is a perspective view of an element for a bodywork part according to the invention during manufacture;

FIG. 2 is a perspective view of the element for the bodywork part of FIG. 1 equipped with a means of protection;

FIG. 3 is a set of diagrams (FIGS. 3a-3e) illustrating various stages of the method of manufacturing the element for bodywork according to a first embodiment;

FIG. 4 is a set of diagrams (FIGS. 4a-4f) illustrating various stages of the method of manufacturing the element for bodywork according to a second embodiment;

FIG. 5 is a perspective view of the bodywork element partially cut along a plane orthogonal to the support sheet obtained according to the second embodiment.

detailed description

There is shown in Figures 1 and 2 an element for a body part designated by the general reference 1 which is being manufactured according to the method as proposed by the present invention. The manufacturing method comprises a first step in which a support element 10, 20 is produced having a first face 11, 21 on which is fixed a support sheet 3 comprising at least one connection member 4. The connection member 4 is made of an electrically conductive plate.

Two embodiments are illustrated respectively in Figures 3 and 4 and will be described in detail later. In both embodiments, a heating track 5 is placed on the support element 10, 20, substantially all of the heating track 5 being placed on the first face 11, 21 of the support element 10, 20, the heating track being formed of an electrically conductive wire. Next, the heating track 5 is connected to the connection member 4 and the support element 10, 20 is placed in a molding chamber of a mold defining the shape of the element for the bodywork part, the first face 11, 21 of the support element 10, 20 facing the inside of the molding chamber and a plastic material is injected into the molding chamber in order to cover the heating track 5.

Now, we will describe the first embodiment which is visible in Figures 3a-3e. According to this embodiment, the support element is a film 10 of plastic material as illustrated in FIG. 3a. This film 10 is produced by extrusion or lamination before fixing a support sheet 3 comprising at least one connection member 4 on a first face 11 of the film 10 as illustrated in FIG. 3b. It is also possible to use an existing film on the market. The film 10 forms a first layer 10 transparent.

As visible in FIG. 3c, a heating track 5 is placed on the film 10, substantially all of the heating track 5 being placed on the first face 11 of the support element. Then, the heating track 5 is connected to the connection member 4 by welding for example. The heating tracks 5 are distributed evenly over the entire surface of the film 10 and are fixed there by gluing or by local melting of the film 10.

A molding step is then carried out in which the support element 10 is placed in a molding chamber of a mold defining the shape of the element for the bodywork part, the first face 11 of the support element 10 being face inside the molding chamber and a plastic material is injected into the molding chamber in order to cover the heating track 5. A second transparent layer 13 is thus obtained as illustrated by FIG. 3d. The molding chamber of the element for a bodywork part is configured so that after molding, the connection member 4 is accessible by a power supply means. Thus, the thickness of the second transparent layer 13 is less than that of the connection member 4.

In order to improve the resistance of the element to UV and to protect it from scratching, it is possible to deposit a coating 6 on a second face 12 of the film which is opposite to the first face 11 as shown in FIG. 3e. This step is also possible in the second embodiment which is illustrated in Figures 4 and 5.

According to the second embodiment of the present invention, the support element is a molded part 20 forming a first transparent layer 20 which is obtained by the following steps: a support sheet 3 comprising at least one connection member 4 is placed in a molding chamber of a mold defining the shape of the molded part 20 as seen in Figure 4a. A first face 31 of the support sheet 3 is placed face inside the molding chamber. When the mold is closed, a plastic material, for example TP, is injected into the molding chamber 3 as shown in FIG. 4b and the molded part 20 is obtained covering the first face 31 of the support sheet 3 as shown in FIG. 4c. The molding chamber of the molded part 20 is configured so that the thickness of the molded part 20 is less than that of the connection member 4 so that the latter is accessible by an electrical supply means.

Subsequently, as seen in Figure 4d, there are several connection members 4 'on a second face 32 of the support sheet 3 which is opposite the first face 31, the connection members 4' being electrically connected to each other by connection means integrated into the support sheet 3. All the connection members 4' are also connected to the connection member 4 which is located on the first face 31.

After the overmolding of the first transparent layer 20 and as visible in FIG. 4e, heating tracks 5 are arranged on the first layer 20 and each connected to a connection member 4′ on the second face 32 of the support sheet 3 by welding. The heating tracks 5 are distributed homogeneously over the entire surface of the first transparent layer 20 and are fixed thereto by gluing or by local melting of the first layer 20.

Finally, the assembly comprising the first layer 20, the support sheet 3 and the heating tracks 5 is placed in a molding chamber defining the shape of the element for a bodywork part, the first face 21 of the first layer 20 being facing inside the molding chamber. Another plastic material, for example thermoplastic polyurethane (TPU), is injected into the molding chamber in order to cover the heating tracks 5 as illustrated in FIG. 4f.

According to the first or the second embodiment, an element 1 for a bodywork part is obtained comprising a first layer 10, 20 of transparent plastic, a second layer 13, 23 of transparent plastic, a heating track 5 arranged between the layers 10, 13; 20, 23 made of transparent plastic and connected to a connection member 4, substantially all of the heating track 5 being in direct contact with the first and second layers 10, 13; 20, 23.

Such an element 1 obtained by the manufacturing method according to the second embodiment can be seen in FIG. 5 which illustrates another aspect of the invention relating to a means of protection 7 of the connection member. The protection means 7 as also illustrated in FIGS. 1 and 2 comprises a base 71 intended to bear against the support sheet 3 and a wall 72 extending from the base 71 and defining a space intended to contain at least partially the connection member 4 so that it is isolated from the plastic material injected during molding while retaining access to it for connection to a power supply.

The invention is not limited to the embodiments shown and other embodiments will be apparent to those skilled in the art. It is in particular possible to arrange several connection members in the first embodiment and to connect them electrically together. It is also possible to provide a ring or an opaque technical area to hide the support sheet when the element is assembled on the vehicle.

List of references

1: element 10, 20: support element (first layer)
13, 23: second layer
10: movie
20: casting
11, 21: first face of the support element
3: backing sheet
31: first face of the support sheet
32: second face of the support sheet
4, 4': connecting device
5: heating track
7: means of protection
71: base
72: wall

Claims (11)

Method for manufacturing an element (1) for a bodywork part comprising successively the following steps:
- Step A: a support element (10, 20) is produced having a first face (11, 21) on which is fixed a support sheet (3) comprising at least one connection member (4).
- Step B: a heating track (5) is placed on the support element (10, 20), substantially all of the heating track (5) being placed on the first face (11, 21) of the support (10, 20) ,
- Step C: the heating track (5) is connected to the connection member (4),
- Step D: the support element (10, 20) is placed in a molding chamber of a mold defining the shape of the element for the bodywork part, the first face (11, 21) of the support (10, 20) facing the inside of the molding chamber and a plastic material is injected into the molding chamber in order to cover the heating track (5). Manufacturing process according to Claim 1, in which the support element (10) is a film (10) of plastic material and step A comprises the following steps:
- a film (10) of plastic material is produced,
- Is fixed on a first face (11) of the film (10) a support sheet (3) comprising at least one connection member (4). Manufacturing process according to any one of the preceding claims, comprising the following step:
- A coating (6) is deposited on a second face (12) of the film, opposite the first face (11). Manufacturing method according to claim 1, in which the support element (20) is a molded part (20) and step A comprises the following steps:
- a support sheet (3) comprising at least one connection member (4) is placed in a molding chamber of a mold defining the shape of the support element (20), a first face (31) of the sheet support (3) facing inside the molding chamber, and a plastic material is injected into the molding chamber in order to obtain a molded part covering the first face (31) of the support sheet (3),
- Is placed on a second face (32) of the support sheet (3), opposite the first face (31), at least one connection member (4). Manufacturing process according to any one of the preceding claims, comprising the following step before step D:
- A means (7) for protecting the connection member (4) is placed on the support sheet so as to at least partially protect the connection member (4) from the plastic material during step D. Manufacturing method according to any one of the preceding claims, in which the heating track (5) is connected to the connection member (4) by welding. Manufacturing process according to any one of the preceding claims, in which the support sheet (3) comprises a plurality of connection members (4) electrically connected to each other by connection means integrated into the support sheet (3) and the steps B and C consist of arranging a corresponding number of heating tracks (5) on the support element (10, 20) and connecting each heating track (5) to a connection member (4). Manufacturing process according to any one of the preceding claims, in which the heating track (5) is fixed to the support element (10, 20) by gluing or by local melting of the support element (10, 20). Manufacturing process according to any one of the preceding claims, in which the heating track (5) comprises a material chosen from among copper, tungsten, or an alloy of copper and tungsten. Manufacturing process according to any one of the preceding claims, in which the support sheet (3) is made from a sheet of silicone, polyolefin (polyethylene or polypropylene), thermoplastic elastomer (TPE), polyester, or polyamide. Element for bodywork part comprising a first layer (10, 20) of transparent plastic, a second layer (13, 23) of transparent plastic, a heating track (5) arranged between the layers (10, 13; 20, 23) of transparent plastic and connected to a connection member (4), substantially all of the heating track (5) being in direct contact with the first and second layers (10, 13; 20, 23).